The pigsty is a major source of odor emissions, and effective on-site odor control is essential for improving the growth environment of pigs and reducing the burden on downstream deodorization systems. In this study, a simulated pigsty environment was used to systematically evaluate the deodorization efficacy of five organic acid salt solutions applied via surface spraying on pig manure. The objectives were to clarify their physicochemical solubilization effects, underlying microbial mechanisms and key functional taxa. Results showed that sodium lactate significantly outperformed the other organic acid salts, achieving an average reduction of 34.4 % +/- 19.4 % in total odor activity over a 48-h cleaning period. This superior performance was primarily due to the effective inhibition of the key odorant pcresol, with an average removal rate of 42.5 % +/- 23.6 % and a peak removal rate of 76.8 % +/- 1.2 % at 48 h. Analyses of the critical micelle concentration and Henry's law constant ruled out solubilization as the primary mechanism of p-cresol removal. Furthermore, changes in microbial biomass did not support the hypothesis that lactate deodorizes mainly via broad-spectrum bacterial inhibition. Instead, the primary mechanism involves enhanced microbial degradation of p-cresol. Notably, the biomass of the key bacterial genus Lentilactobacillus increased by 8.1-217.9-fold, promoting a microbial community that includes Faecalibaculum, Bifidobacterium, and Lachnospiraceae NK4A136_group. This community disrupts the stability of the odor-producing microbial symbiotic network through negative interactions. This study provides a new solution for controlling odor emissions from pig manure by identifying key microbial symbiotic mechanisms involved in odor production and inhibition.
Thermocatalysis is the core route for converting biomass and plastic wastes into syngas. However, tar decomposition is endothermic, requiring high temperatures that promote sintering and coking. Therefore, developing low-temperature catalysts with both high activity and stability remains a key challenge. Herein, we synthesized a small-sized dual-phase NiFe/CoFe nanoalloy particle confined within a pyrolytic carbon matrix, by leveraging the lattice distortion of the dual-phase structure to restrict the migration of nanoparticles. At 650 degrees C, the catalyst achieves 95.01 % tar conversion and produces syngas at a yield of 68.19 mmol.g(-1) with > 90 % selectivity, while exhibiting high stability. This performance notably surpasses that of monometallic, bimetallic alloy and NiFeCo solid solution catalysts. The superior performance stems from its unique nanostructure. The formation of dual NiFe and CoFe active phases induces a competitive nucleation effect, producing small nanoparticles. Compared to the monophasic NiFe and CoFe catalysts, this grain refinement enhances the metal dispersion and metallic active surface area by up to 1.54 - 7.25 and 4.89 - 27.76 times, respectively. Furthermore, this structure enhances oxidation resistance, minimizing the loss of zero-valent active metals. These synergistic advantages contribute to its outstanding performance, offering new insights for designing compact nanocatalysts in energy and environmental applications.
In municipal solid waste incineration, flue gas temperatures in the air pollution control (APC) segment typically range from 120 to 180 °C, making low-temperature catalytic decomposition of chlorobenzenes (CBzs) crucial for emission control. Despite their widespread use, the decomposition mechanisms of transition metal catalysts under these conditions remain unclear. Here, using a Ni single-atom catalyst (Ni@rGO) as a model system, we reveal that CBz degradation at 150 °C proceeds predominantly via hydrodechlorination, accompanied by an extensive Cl-shift process in the CBz skeleton. This rearrangement optimizes adsorption geometry at the active sites, increases surface coverage, and stabilizes adsorption without disrupting the aromatic ring. Density functional theory (DFT) calculations show that the Cl-shift originates from the unique η2-C coordination between Ni and CBzs, with a directional preference for chlorine-substituted carbon atoms. The Ni-CBz complexes undergo continuous coordination-isomerization cycles, reducing C-Cl bond energy, alleviating steric hindrance, and thereby accelerating low-temperature decomposition. Leveraging these synergistic effects, Ni@rGO achieves a CBz decomposition efficiency of 98.6% at 150 °C with ultralow Ni loading. To our knowledge, this represents the first report of a Ni single-atom-driven Cl-shift mechanism in halogenated aromatic degradation.
This research utilized food waste (FW) as substrate, innovatively developed a directional multienzyme applied for accelerating FW hydrolysis and composting, and an in situ enzymatic hydrolysis combining in composting has been developed to manage FW. Results showed that the composting was achieved at 4 days and the humification index was increased by 2.60 compared with that of without enzymatic hydrolysis. FTIR analysis revealed that following multienzyme pretreatment, the primary constituents of FW, including protein, starch and lipid, underwent structural breakdown, among which protein exhibited the higher susceptibility to multienzyme action and was the first to disintegrated, and the structure also became looser. Moreover, the total antibiotic resistance gene (ARGs) was reduced more than 90 % in the proposed composting process. Analysis of microbial communities and metagenomes showed that multienzyme pretreatment reshaped microbial communities towards favoring FW hydrolysis and humification. The engineering application analysis further implied that the proposed composting approach is scale flexible, engineering applicable, economic viability and environmentally sustainability. It was anticipated that this study has the potential to trigger a paradigm shift in future in-situ treatment of FW to achieve full resource recovery towards zero solid discharge.
Hydrothermal treatment of septic sludge can result in the transfer of significant amounts of dissolved organic matter (DOM) into the hydrothermal liquid (HL). However, there is a lack of research exploring the relationship between temperature-sensitive fractions of DOM in HL and ecological risks. In this study, spectroscopic techniques combining two-dimensional correlation spectroscopy (2D-COS), self-organizing maps (SOM) and structural equation modeling (SEM), respectively, were employed to investigate temperature-sensitive DOM and its potential correlation with phytotoxicity at five process temperatures (180-340 °C). The findings revealed that DOM content peaked at 260 °C, measuring 7625 mg·CL-1. At peak levels, the concentrations of chemical oxygen demand, ammonium nitrogen, total nitrogen, and total phosphorus in the HL reached 16900 mg L-1, 34.8 mg L-1, 1920 mg L-1 and 756 mg L-1, respectively. Results from EEM-PARAFAC-SOM indicated that temperature significantly influences the variations in fluorescent components within DOM. Additionally, 2D-COS analysis identified conjugated structures and critical turning points at 220 °C and 300 °C. Notably, the -CO-NH- functional group, which is closely associated with aromatic protein II, exhibited the highest sensitivity to temperature changes. Wheat seed germination experiments revealed that the DOM sample at 180 °C exhibited the most pronounced inhibition of wheat root length, while demonstrating the least effect on germination. In contrast, seed growth was most severely impaired at 340 °C. SEM analysis revealed the influence of temperature-both direct and indirect-on the properties of DOM, identifying aromatic protein I as the primary determinant limiting seed germination. This research provides valuable insights for the management and utilization of HL.
